The CPU heatsink needs to be removed first. Release the hold down mechanism first. Next, remove the heatsink from the CPU. This is done be twisting slightly the heatsink in clockwise and counter clockwise direction until the thermal material breaks loose. Pulling up and out can damage the CPU socket and CPU if you pull everything out of the socket without first removing the heatsink.
It’s a pretty much new build, I built it but the motherboard needs a bios update that I didn’t know about so taking it appart and now it’s completely stuck.